Additives as a major source of radiolytic organic byproducts of polyvinyl chloride (PVC). (November 2021)

• Record Type: Journal Article
• Authors: Chantreux, Mathilde; Ricard, Denise; Asia, Laurence; Rossignol, Stéphanie; Wong-Wah-Chung, Pascal
• Is Part Of: Radiation physics and chemistry. Volume 188(2021)
• Publication Date: 2021-11
• Subjects: PVC -- Radiolysis -- Degradation products -- Additives -- DINP plasticizer; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2021.109671
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: Polyvinyl chloride (PVC), one of the most polymeric materials present in the radioactive waste, is exposed to radiooxidation process during disposal and generates many byproducts. Commercial PVC materials usually contain many additives to provide desired properties and to improve their stability during shaping and lifetime. The additives generally delay PVC radiolysis limiting the formation of some PVC transformation compounds, but they can indubitably generate byproducts as well. Hence, the present work investigates the role of the additives in formulated PVC on the nature and kinetics of the released radiolytic compounds. Four PVC samples, one resin, two PVC formulated on purpose and one commercial PVC containing different additives (at least di-isononyl phthalate (DINP) as plasticizer) were exposed to γ irradiation. Analyses by thermal desorption-GC-MS and solvent extraction coupled with GC-MS were undertaken to identify radio oxidative products. Higher amounts of volatile and non-volatile organic compounds were detected in formulated PVC compared to PVC resin. Some are products coming from the degradation of the polymer chain while the others result mainly from the radiolytic degradation of DINP plasticizer. Commercial PVC containing the widest range of additives (among other lubricants) produced additional byproducts coming from their degradation. Based on the identification and evolution of the radio oxidized products, mechanistic pathways involved in the radiolytic degradation of formulated PVC are proposed. Highlights: Identification of 29 PVC radiooxidation products by TD-GC-MS and GC-MS. Type and quantity of byproducts are controlled by PVC formulation. Alcohols and carboxylic acids from C4 to C9 are formed by plasticizer degradation. Dicarboxylic acids from C6 to C9 originate from lubricant degradation.